As a control valve of this type, JP2010-026825A discloses a poppet-type pressure reducing valve.
A poppet-type pressure reducing valve disclosed in JP2010-026825A includes a seat member through which fluid flowing from a primary port to a secondary port passes, a poppet valve that is provided so as to be movable in the axial direction relative to the seat member, a spring that biases the poppet valve to the valve opening direction, a spring that biases the poppet valve to the valve closing direction, and a piston that is linked to the poppet valve.
The piston disclosed in JP2010-026825A includes a secondary-pressure receiving surface that receives secondary pressure of the secondary port and a pilot-pressure receiving surface that receives reference pilot pressure. The piston moves to a position at which the secondary pressure and the pilot pressure are balanced, thereby changing the resistance applied to the flow of the fluid between the poppet valve and the seat member to adjust the secondary pressure to a constant pressure.